At which university did Richard Feynman teach before joining Caltech?

Before joining Caltech, Richard Feynman taught at Cornell University. He became a professor of theoretical physics there in 1945, after his wartime work at the Los Alamos Laboratory during the Manhattan Project.

Cornell was an important setting for Feynman’s postwar scientific development. Working with physicist Hans Bethe, he advanced his approach to quantum electrodynamics, the theory describing interactions between light and charged particles. The work eventually helped earn him the 1965 Nobel Prize in Physics, shared with Julian Schwinger and Sin-Itiro Tomonaga.

Feynman left Cornell for the California Institute of Technology in 1950. That sequence is sometimes confused because Princeton was also central to his early career: he earned his doctorate there in 1942, but he did not teach there immediately before Caltech. Likewise, Cornell was not merely a brief visiting appointment; it was his principal academic post from 1945 until 1950.